If the accent was genuine, I don't think as many would give a fuck.
It's that it's changed in her YouTube career, in an area that isn't even that accented. You could move to the most Boston accent part of Boston, and if you're an adult nothing about you should change. Kids pick up accents pretty early, most of it before they can even speak.
And they might be tweaked a bit through some of adolescence, but you're not going to randomly start saying lahh when the rest of the ah and e sounds are still neutral.